Greener Approaches for Synthesis of Bioactive Thiadiazole Scaffolds

Thiadiazole is a paradigm of five membered heterocyclic compound that contains two nitrogens and one sulphur as heteroatoms with molecular formula C2H2N2S. Thiadiazole is mainly present in four isomeric forms such as 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole and 1,3,4-thiadiazole. Out of these isomers, 1,3,4-thiadiazole has attracted remarkable attention in the field of medicinal chemistry. Some of the drugs containing 1,3,4-thiadiazole moiety are used clinically and are available in the market including Sulphamethizole (Antibacterial), Acetazolamide (Diuretic), Azetepa (Antineoplastic), Cefazolin (Antibiotic), Megazol (Antiprotozoal), Atibeprone (anti-depressant). Several greener approaches are applied for the synthesis of thiadiazole scaffolds including microwave irradiation, ultrasonic irradiation, grinding, ball milling technique, etc. These methods are eco-friendly, nonhazardous, reproducible, and economical approach. Based on these Green chemistry approaches, thiadiazole derivatives are synthesized from thiosemicarbazide. The functionalization of these heterocyclic compounds generates thiadiazole derivatives with diverse chemical structures. This review covers green synthesis, biological potentials, and structure activity relationship study of thiadiazole analogs.